The present invention relates to an image-forming apparatus which is controlled to stop to avoid a situation where the adherence between toner of the image pattern a in the non-image area and a photoreceptor, intermediate transfer member or a second transfer roller increases, so as to keep the inside of the apparatus clean and to obtain clean images. Here, the image pattern xcex1 is an image which inevitably forms when an image forming operation has stopped or an image pattern created in the non-image area which comes after the image area before the image forming operation is stopped and used for optimizing the quality of the normal image by detecting the density, position, etc. of the image.
There is a well-known image-forming apparatus which forms a toner image on a photoreceptor having charging, exposing, and reversal developing means in its periphery, transfers (i.e. first transfer) the toner image onto an intermediate transfer member, and then transfers (i.e. second transfer) the toner image from the intermediate transfer member onto transfer material, such as transfer paper or the like used as recording material. This kind of apparatus uses a two-component developer which includes toner having the same charging polarity as that of the photoreceptor so as to perform reversible deposition. In order to prevent a two-component developer carrier from adhering to the photoreceptor, the developing bias is impressed before charging is started when an image forming operation starts and then the developing bias is turned off after charging has been finished when the image forming operation stops. This causes the toner to adhere to the area located before and after the charged area on the photoreceptor in a belt-like appearance. If the adhering toner (especially, the toner that has adhered when the image forming operation stopped) remains on the photoreceptor or the intermediate transfer member, the toner adherence increases causing an insufficient cleaning, which results in poor image quality when the next image is printed. Further, if the adhering toner remains sandwiched between two members or remains receiving heat from the fixing unit, etc., the adherence between the toner and a transfer member, such as an intermediate transfer member, photoreceptor, or a transfer roller, further increases causing an insufficient cleaning, which results in poor image quality. Furthermore, if the toner in the image area remains on a photoreceptor or an intermediate transfer member when transfer material, such as transfer paper or the like, jams, the same thing can happen. Especially, if the adhering toner remains sandwiched between two members or remains receiving heat from the fixing unit, etc., the adherence between the toner and a transfer member, such as an intermediate transfer member, photoreceptor, or a transfer roller, further increases causing an insufficient cleaning, which results in poor image quality. Those cases happen frequently.
The main purpose of the present invention is to provide an image-forming apparatus for forming a toner image on a photoreceptor, primarily transferring the toner image on the photoreceptor onto an intermediate transfer member and secondarily transferring the toner image from the intermediate transfer member onto transfer material, such as transfer paper or the like used as recording material, which does not have the problem described above. That is to say, the main purpose of the present invention is to provide an image-forming apparatus which does not stop, when a toner image exists in the non-image area and the toner image remains sandwiched between a photoreceptor and an intermediate transfer member or the intermediate transfer member and a second transfer member, so as to prevent the adherence between each member and the toner from increasing, thereby preventing image problems which affect the creation of the next image from occurring.
(1) An image-forming apparatus for forming a toner image on a photoreceptor having charging, exposing and developing means in its periphery, primarily transferring said toner image onto an intermediate transfer member, and then secondarily transferring said toner image from said intermediate transfer member onto transfer material, comprising cleaning means for removing residual toner which has adhered to the downstream-side surface of said intermediate transfer member in its rotational direction after the second transfer position, further comprising controller for controlling a first transfer voltage or current so that most of the toner image pattern a which has been formed in the non-image area on said photoreceptor is transferred onto said intermediate transfer member and stored thereon and also stopping said intermediate transfer member after the toner which adhered to said intermediate transfer member has been removed.
(2) An image-forming apparatus for forming a toner image on a photoreceptor having charging, exposing and developing means in its periphery, primarily transferring said toner image onto an intermediate transfer member, and then secondarily transferring said toner image from said intermediate transfer member onto transfer material, comprising cleaning means for removing residual toner which has adhered to the downstream-side surface of said photoreceptor in its rotational direction before the first transfer position, further comprising controller for controlling a first transfer voltage or current so that most of the toner image pattern a which has been formed in the non-image area on said photoreceptor remains on said photoreceptor and also stopping said photoreceptor after the toner which has adhered to said photoreceptor has been removed.
(3) An image-forming apparatus, having a second transfer member, for forming a toner image on a photoreceptor having charging, exposing and developing means in its periphery, primarily transferring said toner image onto an intermediate transfer member, and then secondarily transferring said toner image from said intermediate transfer member onto said transfer material, comprising controller for stopping said photoreceptor and said intermediate transfer member at a position where the toner image pattern a which has been formed in the non-image area on said photoreceptor when said apparatus was stopped is not sandwiched between the contacting parts of said photoreceptor and said intermediate transfer member.
(4) An image-forming apparatus according to means (3), comprising a roller or belt for making said second transfer member come in contact with said intermediate transfer member, further comprising controller for stopping said intermediate transfer member at a position where the toner image pattern xcex1 which has been formed in the non-image area on said photoreceptor when said apparatus was stopped is not sandwiched between the contacting parts of said second transfer member and said intermediate transfer member.
(5) An image-forming apparatus according to Means (4), comprising a roller or belt for making said second transfer member come in contact with said intermediate transfer member, further comprising controller for stopping said intermediate transfer member after the toner image pattern xcex1 which has been formed in the non-image area when said apparatus was stopped has passed the contacting parts of said photoreceptor and said intermediate transfer member and is located at a position before the contacting parts of said second transfer member and said intermediate transfer member.
(6) An image-forming apparatus for forming a toner image on a photoreceptor having charging, exposing and developing means in its periphery, primarily transferring said toner image onto an intermediate transfer member, and then secondarily transferring said toner image from said intermediate transfer member onto said transfer material, comprising controller for controlling a first transfer voltage or current so that most of the toner image pattern a which has been formed in the non-image area on said photoreceptor before said apparatus is stopped is transferred onto said intermediate transfer member and stored thereon and also stopping said intermediate transfer member so that the toner image does not remain at a position close to a fixing unit.
(7) An image-forming apparatus for forming a toner image on a photoreceptor having charging, exposing and developing means in its periphery, primarily transferring said toner image onto an intermediate transfer member, and then secondarily contact-transferring said toner image from said intermediate transfer member onto transfer material, comprising cleaning means for removing residual toner which has adhered to the downstream-side surface of said intermediate transfer member in its rotational direction before the second transfer position, further comprising controller for releasing the press-contact of said intermediate transfer member with a secondary contact transfer member when a paper jam has occurred, controlling a first transfer voltage or current so that most of the residual toner image is transferred onto said intermediate transfer member and stored thereon, and also stopping said intermediate transfer member after the toner which has adhered to said intermediate transfer member has been removed.
(8) An image-forming apparatus for forming a toner image on a photoreceptor having charging, exposing and developing means in its periphery, primarily transferring said toner image onto an intermediate transfer member, and then secondarily contact-transferring said toner image from said intermediate transfer member onto transfer material, comprising controller for releasing the press-contact of said intermediate transfer member with a secondary contact transfer member when a paper jam has occurred, and then stopping said intermediate transfer member and said photoreceptor at a position where the residual toner image is not sandwiched between the contacting parts of said photoreceptor and said intermediate transfer member.
(9) An image-forming apparatus for forming a toner image on a photoreceptor having charging, exposing and developing means in its periphery, primarily transferring said toner image onto an intermediate transfer member, and then secondarily contact-transferring said toner image from said intermediate transfer member onto transfer material, comprising controller for releasing the press-contact of said intermediate transfer member with a secondary contact transfer member when a paper jam has occurred, and then stopping said intermediate transfer member so that the toner image so that the residual toner image on said intermediate transfer member does not remain at a position close to a fixing unit.
As described in Means (1) or (7), it is possible to prevent image problems by controlling an image-forming apparatus to transfer most of the untransferred toner image which has been formed in the non-image area or at a time of a jam onto an intermediate transfer member and store it thereon, and then remove the residual toner on said intermediate transfer member by a cleaning device, such as a blade, etc., and finely stop the apparatus.
In Means (8), when a jam has occurred, an image-forming apparatus is controlled to stop in a state where the toner image on an intermediate transfer member is not located on the first transfer contacting parts (i.e. the contacting parts of a photoreceptor and said intermediate transfer member) and also the press-contact of the second transfer roller has been released. Consequently, it is possible to prevent the toner adherence from increasing.
Further, as described in Means (2), it is possible to prevent image problems by keeping most of the untransferred toner image which has been formed in the non-image area or at a time of jam on a photoreceptor without transferring the image onto an intermediate transfer member and then removing the residual toner on said photoreceptor by a cleaning device, such as a blade, etc., and finally stopping the apparatus. Normally, the distance between the first transfer position and the cleaning position of the photoreceptor is shorter than the distance between the first transfer position and the cleaning position of the intermediate transfer member. Therefore, according to Means (1), the time duration for running the image-forming apparatus is shorter, which improves the durability of various components.
As described in Means (3), it is possible to prevent image problems by stopping a photoreceptor at a position where the adhering toner in the non-image area does not remain sandwiched between the contacting parts (i.e. first transfer nipping part) of an intermediate transfer member and said photoreceptor. In this case, when there is a sufficient distance between a developing part and a first transfer nipping part, stopping said photoreceptor at this position requires less time to rotate said photoreceptor, etc., which improves the durability. However, it is difficult to create a sufficient clearance between the developing part and the first transfer nipping part when the photoreceptor-peripheral area is made compact. But, it is possible to reduce the time required for said photoreceptor to rotate while making the photoreceptor-peripheral area compact by stopping an intermediate transfer member at a position which is located before, preferably right before, (i.e. on the downstream side) the first transfer nipping part (i.e. first transfer position) where the adhering toner remains. Further, when a second transfer nipping part is made by a contact transfer member, such as a transfer roller or a transfer belt, as described in Means (4), it is possible to prevent image problems by stopping the intermediate transfer member at a position where the adhering toner in the non-image area does not remain sandwiched between the contacting parts (i.e. second transfer nipping part) of said intermediate transfer member and a second transfer member. Furthermore, as described in Means (5), in addition to the structure of Means (4), by controlling the stop position of said intermediate transfer member so that it stops before the toner image on said intermediate transfer member comes to the second transfer position, it is possible to reduce the time required for rotating the photoreceptor, etc., which improves the durability.
Furthermore, when said intermediate transfer member is stopped with the adhering toner stored thereon, as described in Means (6) or (9), it is possible to prevent image problems by controlling the stop position of said intermediate transfer member so that it is not exposed to the heat mainly caused by a fixing unit, for example, high temperatures exceeding the toner""s glass transition point which appear between 50xc2x0 C. and 60xc2x0 C. centigrade.